1. Field of the Invention
This invention relates to x-ray film cassettes which are opaque to light but at least one side of which is transparent to X-rays and which have a window for allowing imaging of information on the film in the cassette, by light.
2. Description Relative to the Prior Art
X-ray film cassettes are known which include a housing for receiving a sheet of X-ray film for exposure to X-rays for imaging a portion of the anatomy. The housing is opaque to light and serves to keep light from the film. It is known that it is very important to associate a sheet of film bearing an image, with the correct patient. To achieve this objective, it is known to image onto the film sheet while it is in the cassette and before processing, details identifying the patient and, perhaps, other information. This imaging of patient identification information is performed with light. U.S. Pat. specification No. 4,313,538 describes a window which is openable to allow imaging of the information and closeable to maintain the light integrity when information is not to be imaged and when the cassette is in the light. It is known that the window may contain a slidable member and that there be a catch for holding the slidable member in the window closed position. The catch is released by a probe associated with a device for projecting a light image of the information onto the film. The probe may also serve for moving the slidable member between its window open and window closed positions.
It is an object of the present invention to provide a superior window for an X-ray cassette.